In our startup, Nuwa Information, We are glad to open our works to open source community.
I wroten a client side compression library using javascript and LZJB algorithm.
It is very good to do compression data stuffs in browser. We release it to public.
You can link to http://code.google.com/p/jslzjb/ for further details.
We use JsLZJB to compress HTML and submit it to our server to process. Our server side implementation, of course, is Python. So we also release PyLZJB library: http://code.google.com/p/pylzjb/
We also hope that is helpful for you.